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Crossopteryx

About: Crossopteryx is a research topic. Over the lifetime, 6 publications have been published within this topic receiving 363 citations.

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Journal ArticleDOI
TL;DR: Fire resistance may interact with competition: it is suggested that differences in fire resistance strategies have important effects on the structure and dynamics of savanna ecosystems.
Abstract: Bark properties (mainly thickness) are usually presented as the main explanation for tree survival in intense fires. Savanna fires are mild, frequent, and supposed to affect tree recruitment rather than adult survival: trunk profile and growth rate of young trees between two successive fires can also affect survival. These factors and fire severity were measured on a sample of 20 trees near the recruitment stage of two savanna species chosen for their contrasted fire resistance strategies (Crossopteryx febrifuga and Piliostigma thonningii). Crossopteryx has a higher intrinsic resistance to fire (bark properties) than Piliostigma: a 20-mm-diameter stem of Crossopteryx survives exposure to 650°C, while Piliostigma needs a diameter of at least 40 mm to survive. Crossopteryx has a thicker trunk than Piliostigma: for two trees of the same height, the basal diameter of Crossopteryx will be 1.6 times greater. Piliostigma grows 2.26 times faster than Crossopteryx between two successive fires. The two species have different fire resistance strategies: one relies on resistance of aboveground structures to fire, while the other relies on its ability to quickly re-build aboveground structures. Crossopteryx is able to recruit in almost any fire conditions while Piliostigma needs locally or temporarily milder fire conditions. In savannas, fire resistance is a complex property which cannot be assessed simply by measuring only one of its components, such as bark thickness. Bark properties, trunk profile and growth rate define strategies of fire resistance. Fire resistance may interact with competition: we suggest that differences in fire resistance strategies have important effects on the structure and dynamics of savanna ecosystems.

249 citations

Journal ArticleDOI
TL;DR: It is concluded that the tribeCinchoneae, in order to be monophyletic, should be restricted to compriseCapirona, Cephalodendron, Cinchona, Cosmibuena, Dolicholobium, Ferdinandusa, Joosia, Ladenbergia, Macrocnemum, andRemijia.
Abstract: Circumscription of the tribeCinchoneae (Rubiaceae) is reconsidered on the basis of a cladistic analysis of structural data comprising 48 characters (164 states). It is concluded that the tribeCinchoneae, in order to be monophyletic, should be restricted to compriseCapirona, Cephalodendron, Cinchona, Cosmibuena, Dolicholobium, Ferdinandusa, Joosia, Ladenbergia, Macrocnemum, andRemijia. It is also suspected, on insufficient evidence, thatMaguireocharis, Pimentelia, andStilpnophyllum belong here.Alseis, Calycophyllum, Schizocalyx, andWittmackanthus form a monophyletic group possibly related to theCinchoneae. A new tribe,Calycophylleae, is proposed to accommodate them.Hillia, which is possibly the sister group of theCinchoneae, is retained in a separate tribe.Coptosapelta, Corynanthe, Crossopteryx, Hymenodictyon, Luculia, Mitragyna, Mussaendopsis, Paracorynanthe, Pausinystalia, andUncaria are referred to the same tribe, for which the nameCoptosapelteae has to be adopted. Probably alsoGreeniopsis belongs here. The generaCigarilla, Coutarea, andExostema, and possiblySyringantha andWernhamia, seem to be most closely related toPortlandia and should be transferred to the tribeCondamineeae. Bouvardia, Coursiana, Danais, Duidiana, Dunnia, Heterophyllaea, Hindsia, Lecanosperma, Manettia, Merumea, Neohymenopogon, andSchismatoclada should be provisionally transferred to the tribeHedyotideae, which is suspected to be polyphyletic, however. No conclusive results were reached concerning the position ofBalmea, Blepharidium, Emmenopterys, andSuberanthus, the position of them remaining uncertain.

67 citations

Journal ArticleDOI
TL;DR: Wood samples of a number of Cinchoneae and Naucleeae sensu Schumann were studied, and the results compared with data found in the literature; the creation of the tribe Coptosapelteae and its inclusion in the Ixoroideae seem to be corroborated by the particular character of the wood anatomy.
Abstract: Wood samples of a number of Cinchoneae and Naucleeae sensu Schumann were studied, and the results compared with data found in the literature. On the whole the representatives of the Cinchoneae appeared to show a rather high degree of similarity among each other with the exception, however, of the genera Coutarea, Exostemma, Corynanthe, Crossopteryx, and Hymenodictyon. The creation of the tribe Coptosapelteae and its inclusion in the Ixoroideae seem to be corroborated by the particular character of the wood anatomy. The restriction of the Naucleeae to Nauclea L. ( Sarcocephalus Afzel.) is not supported by the anatomy of the wood.

24 citations

Journal ArticleDOI
01 Aug 2011-Taxon
TL;DR: A large number of monotypic genera with unique apomorphic characters have been difficult to place in the morphology-based classifications of the coffee family (Rubiaceae) and this work rigorously assessed the subfamilial relationships.
Abstract: Many monotypic genera with unique apomorphic characters have been difficult to place in the morphology-based classifications of the coffee family (Rubiaceae). We rigorously assessed the subfamilial ...

22 citations

Journal ArticleDOI
01 Aug 2009-Taxon
TL;DR: The genus Alberta is found to be paraphyletic as presently circumscribed and the new genus Razafimandimbisonia Kainul is proposed by C. & B. Bremer to accommodate the Malagasy species.
Abstract: The tribe Alberteae, presently classified in the subfamily Ixoroideae (Rubiaceae), has historically been an artificial grouping of genera. In the present study, phylogenetic analyses of the chloroplast DNA markers rbcL, ndhF, trnS-G, trnT-F and trnH-psbA as well as the ITS region of the nuclear ribosomal DNA, are done to assess the delimitation of Alberteae. The resulting phylogenetic hypothesis is highly resolved, with most clades strongly supported. The genus Alberta is found to be paraphyletic as presently circumscribed. As a consequence, we propose the new genus Razafimandimbisonia Kainul. & B. Bremer to accommodate the Malagasy species. The newly delimited Alberta is distinguished by having two calycophylls that expand after anthesis as well as awl-shaped stigma lobes. Razafimandimbisonia is distinguished from the remaining Alberteae by having dehiscent fruits and anthers without basal appendages. We demonstrate that the genera Airosperma, Boholia and Crossopteryx are not associated with Alberteae, as has previously been suggested. Alberteae is considered restricted to the genus Alberta endemic to Southeast Africa, and the two Malagasy endemic genera Nematostylis and Razafimandimbisonia.

19 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20191
20111
20091
19971
19911
19701